Mikael Abrahamsson <swmike <at> swm.pp.se> writes: > Does seekmark use barriers to assure that data has actually been written? > In that case it could be that 2.6.18 has different behaviour from 2.6.32 > when it comes to barriers and that explains the speed difference. > Mikael, looks like you were right. Aside from seekmark I was also testing with random dd to not relay on single measurment tool. I run found out it is not only related to raid but to block devices in general. I run 'hdparm -W0 /dev/sda' on cetos5 and got the same poor behavior of centos6. Anyway I cannot still find a way to enable drive write cache on centos6. hdparm reports it is enabled but results are the same (poor) no matter if after 'hdparm -W0 /dev/sda' or 'hdparm -W1 /dev/sda' so now I am guessing write cache must be blocked somewhere in the kernel. I still cannot find a way to enable write cache in centos 6. Booting with 'barriers=off' kernel parameter and 'barrier=0' in fstab does not help. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
